Assay systems for oncogenic transformation in vitro have a major role to play in helping to understand the complex processes of radiation carcinogenesis. A number of systems have been developed, based on short term cultures of hamster embryo cells or established cell lines from the mouse. While transformation by x-rays has been demonstrated in human cells, a repeatable quantitative assay has not yet been developed. The proposed workshop will bring together scientists from Europe, the United States and Japan to review existing data on radiation-induced transformation, to discuss basic mechanisms at the molecular level and to speculate upon the extent to which data from these model systems can be extrapolated to the human situation. The meeting is planned for September\9-11th, 1985 at an Oxford Collge in the United Kingdom. The size of the meeting will be small, and participation will be by invitation only in order to preserve the workshop format. The purpose of this grant application is to ensure the presence of a U.S. delegation at this meeting.